British prosecutors charged a policeman with misconduct Tuesday after a dispute over whether a senior politician insulted police officers outside the prime minister's office grew into a crisis about the integrity of Britain's largest force.

Prosecutors said Keith Wallis is being charged with sending an email to a lawmaker that falsely claimed that he witnessed the Sept. 19 incident. Prosecutors also allege that Wallis arranged for his nephew to support his story.

The case revolved around Andrew Mitchell, a senior Conservative Party politician who was accused of swearing at police and insulting them when they refused to open the gate outside the prime minister's Downing Street office so that he could ride his bicycle through it. Mitchell was accused of calling them "plebs" — a condescending term for working-class people that struck a nerve in this class-sensitive society.

Mitchell admits he lost his temper and swore as he tried to make his way through the gate, but he has long denied using the term "pleb" or telling officers to "learn your place." He has described the words attributed to him as "a bad caricature of what an ill-mannered 1930s upper-class lout might say."

In the storm that followed, he was forced to resign, but questions were raised about the police account. The so-called "plebgate" incident challenged the ethics of Scotland Yard's police, whose reputation had already been battered by corruption exposed in the phone hacking scandal.

But prosecutors failed to make a determination on who they thought was telling the truth — noting that no independent accounts exist of what occurred. CCTV images failed to settle the issue as footage is consistent with both accounts.